1. Calculate the electric current of a 10 Watt lamp designed for 12 Volt.
Known :
Power (P) = 10 Watt
Voltage (V) = 220 Volt
Wanted : Electric current
Solution :
Lamp power = 10 Watt = 10 Joule/second
The equation below shows the relation between the electric power (P), electric potential (V) and electric current (I) stated in formula below :
P = V I
Electric current :
I = P / V = 10 / 220 = 1/22 = 0.045 Ampere
[irp]
2. Calculate the electric power according to the electric circuit below.
Known :
Resistor 1 (R1) = 6 Ω
Resistor 2 (R2) = 6 Ω
Electric voltage (V) = 24 Volt
Wanted : Electric power
Solution :
Equivalent resistor :
R1 and R2 are connected in series. The equivalent resistor :
R = R1 + R2 = 6 Ω + 6 Ω = 12 Ω
The electric current :
I = V/R = 24/12 = 2 Ampere
Electric power :
P = V I = (24)(2) = 48 Watt = 48 Joule/second
[irp]
3. Calculate the electric current of a 3 kiloWatt designed for 150 Volt.
Known :
Electric power (P) = 3 kiloWatt = 3000 Watt
Electric voltage (V) = 150 Volt
Wanted : Electric current (I)
Solution :
Relation of the electric power (P), electric potential (V) and electric current (I) stated in formula below :
P = V I
The electric current :
I = P / V
I = 3000 Watt / 150 Volt
I = 20 Ampere